1. Field of the Invention
The present invention relates to a method and a system for extracting, adding and/or otherwise manipulating a three dimensional (3D) region of interest from a stack of two dimensional scan slices. In particular, the present invention provides a method and an apparatus for obtaining a 3 D shape for visualization either as is or for volume visualization by masking out undesirable parts of a data set stored in two dimensional scan slices such as a stack of medical scan slices.
2. Description of the Related Art
To extract a three-dimensional (3D) region of interest from a stack of medical scan slices is still a challenging task nowadays. The main difficulty is that there is no robust automatic algorithm that can handle all the different situations and applications. When automatic methods fail, human intervention is usually unavoidable for extracting desired area or regions of interest. However, without convenient tools, it is a tedious job for human being to go through hundred or thousand of slices just to extract regions of interest. A 3D shape can be reconstructed from these contours using various methods. There are several ways to use the reconstructed 3D shape. It can be visualized as is. It can be used as spatial rendering attributes in volume visualization. It can be used as a mask to remove unwanted parts from a data set and reveal obscured portion of the data set.
A general flow of a typical application is shown in FIG. 1.
There are plenty of algorithms for each of the steps. However, it would be desirable to find algorithms that can overcome the following limitations and provide users with a robust tool for the extraction.
Since in medical domain applications, the data usually is in the form of parallel slices based on the medical scan devices. The regions of interest are outlined as 2D contours from these slices using various automatic or interactive methods. This leads to approaches for reconstructing 3D objects based on these series of parallel 2D contours. There are lots of research papers dealing with this problem. Most of the approaches use triangular tilting but have to deal with various correspondence problems, branching problems, and the tiling problems [1].
Sometimes, the most significant features are not revealed in the direction of the parallel slices but in other directions. It is to the best of user interactive efficiency and shape fidelity if the user can outline the significant features along that direction. However, there are very few methods that can handle non-parallel contour surface reconstruction.
Another important factor to the success of 3D object extraction is interactivity. A user requires quick visual feedback to correct some mistakes or add more contours in contour drawing stage. To achieve interactive speed for quick updating and adjusting of the whole process is also a very challenging job.
It is therefore desirable to combine and modify several advanced techniques to help user extract volume of interest very easily and quickly.
It is therefore an object of the present invention to provide a method and a system for more rapidly developing 3D shapes from two dimensional scan slices for (1) visualization; (20) removal of obscuring portions of the two dimensional data set e.g. scan slices, in order to better visualize the remaining data set as a 3D image; and (3) to permit repetition of this process in order to refine the quality of the produced 3 D shape.
It is another object of the present invention to provide a 3D shape of organs and body parts that is faster to produce particularly when required during medical procedures and that produces by better resolution through repetition by repeating the process in a faster time interval then is currently available.
It is yet another object of the present invention to utilize livewire techniques, shape reconstruction techniques including variation interpolate techniques to more rapidly derive 3D shapes from 2D scan slices and from delineated 2D contours.
Other objects of the present invention will become apparent from the foregoing drawings and description.